I'll mention something that may help if you want to stay with PDF
If you look in GREDIR/bin/src you will see a file gviewdoc.4gl which gets compiled into GREDIR/lib
This is what is used when viewing a report with fgl_report_selectPreview(TRUE)
In there you will see it uses the shellexec frontcall to view the report file. Shellexec is the equivalent of double-clicking on a file and using the default application to open the file. Some little known functionality about shellexec frontcall is that if you specify a second argument you do the equivalent of right-clicking on file and selecting an action e.g. print
So you might be able to get what you want for PDF by adding a second argument to the shellexec frontcall in gviewdoc.4gl. Some discussion here
https://4js.com/fjs_forum/index.php?topic=140.0Reuben